Field of Endeavor
The present application relates to additive manufacturing and more particularly to additive manufacturing via direct writing of pure metal and eutectics through latent heat position control.
State of Technology
This section provides background information related to the present disclosure which is not necessarily prior art.
The disclosed apparatus, systems, and methods provide an improvement over the state-of-the-art because it can print semi-solid pure metals (non alloys) and eutectic alloys. Prior art has been limited to non-eutectic alloys because they have thermodynamically stable semi-solid states over a range of temperatures. The semi-solid states for pure metal and eutectic alloys only exist at a single temperature. The Prior Art “Metal Solid Freeform Fabrication” described in the Journal Article, “Metal Solid Freeform Fabrication Using Semi-Solid Slurries,” by Christopher S. Rice, Patricio F. Mendez, and Stuart B. Brown, in JOM, December 2000 describes printing metal alloys in the semi-solid regime. They do this by controlling temperature over some distance to produce a thermodynamically stable semi-solid alloy.
The inventor's apparatus, systems, and methods allow the production of non-thermodynamically stable semi-solid states in pure and eutectic metals by controlling heat flow into the alloy. The prior art printing of eutectic alloys using fused deposition modeling. This technique is fundamentally different from direct writing because it uses a filament that is locally heated to melting and then uses the pressure of the solid filament to extrude, relying on rapid cooling of the liquid to maintain its shape. In this invention, the metal charge is fully melted and heat flow into the metal is controlled over some distance in order to extrude a semi-solid metal that retains its shape as it is extruded.
U.S. Pat. No. 6,722,872 for a high temperature modeling apparatus provides the state of technology information reproduce below.
Examples of apparatus and methods for making three-dimensional models by depositing layers of flowable modeling material are described in Valavara U.S. Pat. No. 4,749,347; Crump U.S. Pat. No. 5,121,329, Batchelder, et al. U.S. Pat. No. 5,303,141, Crump U.S. Pat. No. 5,340,433, Batchelder, et al. U.S. Pat. No. 5,402,351, Crump et al. U.S. Pat. No. 5,503,785, Abrams et al. U.S. Pat. No. 5,587,913, Danforth, et al. U.S. Pat. No. 5,738,817, Batchelder, et al. U.S. Pat. No. 5,764,521 and Comb et al. U.S. Pat. No. 5,939,008, all of which are assigned to Stratasys, Inc., the assignee of the present invention. An extrusion head extrudes heated, flowable modeling material from a nozzle onto a base. The base comprises a modeling substrate which is removably affixed to a modeling platform. The extruded material is deposited layer-by-layer in areas defined from the CAD model, as the extrusion head and the base are moved relative to each other in three dimensions by an x-y-z gantry system. The material solidifies after it is deposited to form a three-dimensional model. It is disclosed that a thermoplastic material may be used as the modeling material, and the material may be solidified after deposition by cooling.
Technology described in the aforementioned patents is commercialized in Stratasys FDM® modeling machines. The extrusion head, which includes a liquefier and a dispensing nozzle, receives modeling material in a solid form. The filament is heated to a flowable temperature inside the liquefier and it is then dispensed through the nozzle. Thermoplastic materials, particularly ABS thermoplastic, have been found particularly suitable for deposition modeling in the Stratasys FDM® modeling machines. A controller controls movement of the extrusion head in a horizontal x, y plane, controls movement of the build platform in a vertical z-direction, and controls the feeding of modeling material into the head. By controlling these processing variables, the modeling material is deposited at a desired flow rate in “beads” or “roads” layer-by-layer in areas defined from the CAD model to create a three-dimensional object that resembles the CAD model. The modeling material thermally solidifies, and the finished model is removed from the substrate.